“The Epoch” is the time at the beginning of time as far
as modern operating systems go.
Unix time, and some versions of
MS-Windows time, count off inexorably the seconds since the epoch. On
systems that store this in a 32-bit integer, time is indeed running
out. Let’s say we wanted to find out when the Unix operating
system, whose 32-bit versions use a 32-bit date, will get into
difficulty. We take a 32-bit integer of all ones, and construct a
Date
around it. The Date
constructor needs the number of milliseconds since 1970, so we
multiply by 1,000:
/** When does the UNIX date get into trouble? */ public class Y2038 { public static void main(String[] a) { // This should yield 2038AD, the hour of doom for the // last remaining 32-bit UNIX systems (there will be // millions of 64-bit UNIXes by then). long expiry = 0x7FFFFFFFL * 1000; System.out.println("32-bit UNIX expires on " + Long.toHexString(expiry) + " or " + new java.util.Date(expiry)); // Why doesn't it? // Try going from msec of current time into a Date long now = System.currentTimeMillis( ); System.out.println( "Passing " + Long.toHexString(now) + " --> " + new java.util.Date(now)); } }
Sure enough, the program reports that 32-bit Unixes will expire in the year 2038 (you might think I knew that in advance if you were to judge by the name I gave the class; in fact, my web site has carried the Y2038 warning to Unix users for several years now). At least Unix system managers have more warning than most of the general public had for the original Y2K problem.
> java Y2038 32-bit UNIX expires on 1f3fffffc18 or Mon Jan 18 22:14:07 EST 2038 Passing e29cfe1432 --> Fri Nov 03 19:08:25 EST 2000 >
At any rate, if you need to convert seconds since 1970 to a date, you know how.
13.58.44.229